Background: Despite the diversity of the studied health outcomes, types and levels of pollution, and various environmental settings, there is substantial evidence for a positive link between urban air pollution and cardiovascular diseases. The objective of this study was to test the associations between air pollutants and the occurrence of acute myocardial infarction (AMI).
Methods and results: Pollutant concentrations (SO2, NO2, and O3) were measured hourly as part of the automated air quality network. Since 1985, an AMI registry (the Toulouse MONICA Project) has been collecting data in the southwest of France. All cases of AMI and sudden and probable cardiac deaths are recorded for subjects 35 to 64 years of age. We studied the short-term exposure effect of pollution on the risk of AMI (from January 1, 1997, to June 30, 1999) using a case-crossover design method. We performed a conditional logistic regression analysis to calculate relative risks (RRs) and their 95% CIs. After adjustment for temperature, relative humidity, and influenza epidemics, the RRs (for an increase of 5 microg/m3 of O3 concentration) for AMI occurrence were significant for the current-day and 1-day-lag measurements (RR, 1.05; 95% CI, 1.01 to 1.08; P=0.009; and RR, 1.05; 95% CI, 1.01 to 1.09; P=0.007, respectively). Subjects 55 to 64 years of age with no personal history of ischemic heart disease were the most susceptible to develop an AMI (RR, 1.14; 95% CI, 1.06 to 1.23). NO2 and SO2 exposures were not significantly associated with the occurrence of AMI.
Conclusions: Observational data confirm that short-term O3 exposure within a period of 1 to 2 days is related to acute coronary events in middle-aged adults without heart disease, whereas NO2 and SO2 are not.